Flashing or chasing large groups of LEDs and figuring voltages
I am playing around with making LED signs. How do I build a circuit to make a parallel string of 50-100 LEDs flash or chase?
Also, when working with a large group of LEDs in parallel, how do I figure the size of DC power supply I need. Especially when there are different color requiring different voltages.
On my first attempt, I used a 4.5 volt wall wart with various resistors between the white and red bulbs til I got a pretty fair brightness on both. But I was scared of frying 200 LEDs in fell swoop, so I would like to learn the proper way. I think I understand Ohms law to calculate the right voltage and amperage for 1 LED, but how does that apply to 100 or 150?